Turret winders are well known in the art. Conventional turret winders comprise a rotating turret assembly which supports a plurality of mandrels for rotation about a turret axis. The mandrels travel in a circular path at a fixed distance from the turret axis. The mandrels engage hollow cores upon which a paper web can be wound. Typically, the paper web is unwound from a parent roll in a continuous fashion, and the turret winder rewinds the paper web onto the cores supported on the mandrels to provide individual, relatively small diameter logs.
While conventional turret winders may provide for winding of the web material on mandrels as the mandrels are carried about the axis of a turret assembly, rotation of the turret assembly is indexed in a stop and start manner to provide for core loading and log unloading while the mandrels are stationary. Turret winders are disclosed in the following U.S. Pat. No. 2,769,600 issued Nov. 6, 1956 to Kwitek et al; U.S. Pat. No. 3,179,348 issued Sep. 17, 1962 to Nystrand et al.; U.S. Pat. No. 3,552,670 issued Jun. 12, 1968 to Herman; and U.S. Pat. No. 4,687,153 issued Aug. 18, 1987 to McNeil. Indexing turret assemblies are commercially available on Series 150, 200, and 250 rewinders manufactured by the Paper Converting Machine Company of Green Bay, Wis.
The Paper Converting Machine Company Pushbutton Grade Change 250 Series Rewinder Training Manual discloses a web winding system having five servo controlled axes. The axes are odd metered winding, even metered winding, coreload conveyor, roll strip conveyor, and turret indexing. Product changes, such as sheet count per log, are said to be made by the operator via a terminal interface. The system is said to eliminate the mechanical cams, count change gears or pulley and conveyor sprockets.
Various constructions for core holders, including mandrel locking mechanisms for securing a core to a mandrel, are known in the art. U.S. Pat. No. 4,635,871 issued Jan. 13, 1987 to Johnson et al. discloses a rewinder mandrel having pivoting core locking lugs. U.S. Pat. No. 4,033,521 issued Jul. 5, 1977 to Dee discloses a rubber or other resilient expansible sleeve which can be expanded by compressed air so that projections grip a core on which a web is wound. Other mandrel and core holder constructions are shown in U.S. Pat. Nos. 3,459,388; 4,230,286; and 4,174,077.
Indexing of the turret assembly is undesirable because of the resulting inertia forces and vibration caused by accelerating and decelerating a rotating turret assembly. In addition, it is desirable to speed up converting operations, such as rewinding, especially where rewinding is a bottleneck in the converting operation.
Accordingly, it is an object of the present invention to provide an improved method of winding a web material onto individual hollow cores.
It is also an object of the present invention to provide an improved turret winder.
Another object of the present invention is to provide a web winding apparatus having a turret winder that can be operated in a continuous manner, wherein core loading, core gluing, web winding, and core stripping can occur as the mandrels move in a closed path.
Another object of the present invention is to provide a turret winder which carries a plurality of mandrels in a non-circular path.
Yet another object of the present invention is to provide a rotatably driven turret assembly for supporting a plurality of mandrels carried in a path about a turret axis, wherein the distance between the mandrels and the turret axis varies as a function of the position of the mandrels about the axis.
Yet another object of the present invention is to provide a method for winding a continuous web of material into individual logs.